Narrowband systems include a number of infrastructure elements for facilitating communications between communication devices. For example, public safety organizations may use specialized communication systems embodied as narrowband radio systems that typically support low-bit-rate digital or analog transmission of audio and/or data streams. An example of such a narrowband network uses an Association of Public Safety Communications Official (APCO) Project 25 (P25) standard in a voice communication system that includes wireless and wired communication devices. Examples of other standards used in systems operating on the narrowband network may include, but are not limited to, Terrestrial Trunked Radio (TETRA), analog FM, Securenet, Digital Mobile Radio (DMR), High Performance Data/High Speed Data (HPS/HSD) Soldier Radio Waveform (SRW), and/or other legacy cellular protocols. The communication devices used in these narrowband systems may be, for example, portable radios for hand held operation, mobile radios for vehicular operation, dispatch consoles and other fixed equipment for console operator positions and wide-area operation, base stations for fixed installations, computer equipment for data communication, or other similar communication entities that communicate with one another via wired and/or wireless networks. Public safety organizations may choose these narrowband systems because they provide improved end-to-end voice quality and efficient group communication, use advanced cryptography, enable centralized logging of calls, and/or are associated with lower delay and higher reliability.
In, for example, a P25 system, a Common Air Interface is used to ensure that communication devices can interoperate at the physical layer and the data link layer. In particular, voice and/or data messages are processed in a transmitting communication device and transmitted over the Common Air Interface to a receiving communication device. Data may be sent with either confirmed delivery or unconfirmed delivery. Confirmed delivery requires that the receiving communication device sends an acknowledgment when the data message is received. After sending a data message with confirmed delivery, if the receiving communication device does not send the acknowledgment, the transmitting radio may then selectively resend the unacknowledged data packets. In some protocols, after sending a data message with confirmed delivery, the receiving radio may send a request for a re-transmission instead of just an acknowledgement. Unconfirmed delivery is used when the transmitting communication device does not require an acknowledgement from the receiving communication device when the receiving communication device receives the data message.
The receiving communication device may be, for example, a multi-channel receiver radio that may simultaneously receive data and/or voice messages on two or more channels. Although the multi-channel receiver radio is configured to receive message on two or more channels, due to the interference from the transmitter, transmitting information on one channel prevents the multi-channel receiver radio from reception on the other channel(s). Therefore, when the multi-channel receiver radio receives a data packet with confirmed delivery, while the radio is sending an acknowledgement receipt for the received data packet on one channel, the radio is prevented from receiving data or voice messages on the other channel(s), even if the channel(s) is receiving real-time data. There are some very expensive hardware-based workarounds involving large and costly duplexers that also solve the interference from the transmitter. However, without these expensive hardware-based workarounds, sending the acknowledgement receipt for the received data packet may prevent the radio from receiving, for example, real-time voice message(s).
Accordingly, there is a need for a method for simultaneously receiving messages on multiple channels in a receiver apparatus, wherein the receiver apparatus is configured to transmit information on one channel without affecting reception on the other channel(s).
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.